From 40d31b8e45421ed1fb6906a9fe2fca1d75f6b6ef Mon Sep 17 00:00:00 2001 From: Ahmad Fatoum Date: Wed, 2 Nov 2022 09:50:17 +0100 Subject: commands: uptime: add note about caveats Normally timer overrun is not that much of a problem, because there where it matters, we usually have an is_timeout() in the loop that reads the timer often enough. This doesn't necessarily hold for the new uptime command and basically anything can happen between subsequent calls and if get_time_ns() is not called often enough during that time, we end up with an inaccurate uptime. Mention this in the extended help text. Signed-off-by: Ahmad Fatoum Link: https://lore.barebox.org/20221102085017.1941580-1-a.fatoum@pengutronix.de Signed-off-by: Sascha Hauer --- commands/uptime.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'commands') diff --git a/commands/uptime.c b/commands/uptime.c index a9a8c650b6..d67538631c 100644 --- a/commands/uptime.c +++ b/commands/uptime.c @@ -66,6 +66,9 @@ static int do_uptime(int argc, char *argv[]) BAREBOX_CMD_HELP_START(uptime) BAREBOX_CMD_HELP_TEXT("This command formats the number of elapsed nanoseconds") BAREBOX_CMD_HELP_TEXT("as measured with the current clocksource") +BAREBOX_CMD_HELP_TEXT("Note: Timekeeping is co-operative. If long running code does") +BAREBOX_CMD_HELP_TEXT("not use delay/is_timeout/get_time_ns/getchar functions") +BAREBOX_CMD_HELP_TEXT("timer may overrun resulting in incorrect results") BAREBOX_CMD_HELP_TEXT("Options:") BAREBOX_CMD_HELP_OPT ("-n", "output elapsed time in nanoseconds") BAREBOX_CMD_HELP_END -- cgit v1.2.1